@ARTICLE{Shvai2018UMJ,
  title     = "Estimation of the best bilinear approximations for the classes
               of ($\psi$, {$B$)-differentiable} periodic multivariable
               functions",
  author    = "Pozharska, K.  and (Shvai K.) ",
  journal   = "Ukr. Math. J.",
  publisher = "Springer Science and Business Media LLC",
  volume    =  70,
  number    =  4,
  pages     = "649--660",
  year      =  2018,
  doi       =  {10.1007/s11253-018-1522-z},
}